A system and a method for recovering oil from an oil-bearing formation wherein the method includes providing a reverse osmosis (RO) unit comprising at least one membrane; feeding a first feed stream having a first salinity content to a first side of the membrane; and feeding a second feed stream having a second salinity content to a second side of the membrane. The method further includes discharging a retentate stream from the first side of the membrane, and discharging a product stream having a controlled salinity content from the second side of the membrane. The method furthermore includes injecting at least a portion of the product stream into the oil-bearing formation, and recovering at least a portion of the oil from the oil-bearing formation.